A wire carries a current directly away from you. Part A Which way do the magnetic – [Free] B44
A wire carries a current directly away from you. Part A Which way do the magnetic field lines produced by this wire point? They point toward the wire. They point parallel to the wire in the direction of the current. They point parallel to the wire opposite the direction of the current. They make circles around the wire. They point away from the wire. Request Answer
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Physics Concept Explained: Magnetic Field Around a Wire
Question:
A wire carries a current directly away from you. Which way do the magnetic field lines produced by this wire point?
Options:
- (a) They point toward the wire.
- (b) They point parallel to the wire in the direction of the current.
- (c) They point parallel to the wire opposite the direction of the current.
- (d) They point away from the wire.
- (e) They make circles around the wire.
Answer with Detailed Explanation:
Step 1: Understand the Magnetic Field Around a Current-Carrying Wire
According to Ampère’s Law and the right-hand rule, the magnetic field lines produced by a straight current-carrying wire form closed loops around the wire.
These loops are perpendicular to the wire and exist in the plane surrounding the wire.
Step 2: Apply the Right-Hand Rule
To determine the direction of the magnetic field lines:
- Point the thumb of your right hand in the direction of the current. In this case, the current is moving away from you (into the page).
- Your fingers curl around the wire. The direction of your curled fingers indicates the direction of the magnetic field lines.
Therefore, the magnetic field lines form concentric circles around the wire.
Step 3: Eliminate Incorrect Options
- Option (a): ❌ Field lines do not point *toward* the wire.
- Option (b) & (c): ❌ Field lines do not run *parallel* to the wire.
- Option (d): ❌ Field lines do not point *away* from the wire in a straight line.
- Option (e): ✅ Correct — the magnetic field lines make circles around the wire.
Final Answer:
(e) They make circles around the wire.